1 BYU Deposition Facility Previous Turbine Accelerated Deposition Facility (TADF) Design Parameters to match: temp, velocity, angle, materials, particle size, chemistry, and concentration Inconel construction allows max jet temperature of 1200  C Exit velocities up to 300m/s – deposition by inertial impaction Target coupons supplied from industry Capability for impingement and film cooling Match net particle throughput 8000 hrs  0.1 ppmw ≈ 4 hrs  200 ppmw

BYU Coupon Holder Cooling Air Thermocouple Coupon w/cooling holes Deposit-laden combustor exhaust at 1183  C Coupons generally held at 45  angle to flow Deposit-laden combustor exhaust at 1183  C 2

3 BYU – Previous Testing Deposition vs. Temperature Deposition increases with gas exit temperature Insulated tests conducted up to 1150  C (i.e., no cooling) No deposition below ~950  C Deposition vs. Cooling Deposition decreases with increasing coupon cooling backside cooling film cooling on surface 3

4 Goal 1: Increase gas temperatures to 1400  C Why? Mimic H class turbine gas temperatures Investigate mechanism changes at higher temperatures Gas temperature affects particle melting Surface temperature affects deposit stickiness & tenacity Examine deposition threshold temperatures with realistic blowing ratios Existing experiments cool surface too much with M=2 Distinguish sweeping effect from surface cooling effect How? Build new shell Reaction Bonded SiC Price ~$4500 Modify coupon holder New design Insulate front face

Temperature Range New Range Previous range of experiments 5

6 BYU – Facility Modification Redesign For 1400  C Cone and Tube Reaction bonded SiC (previously Inconel) New Max Operating Temp = 1500  C No problems with thermal shock on startup and shutdown New Cone and Tube Connection to base 1.2 m I.D. = 2.5 cm SiC Cone Clamping Ring

7 BYU – New Coupon Holder Redesign For 1400  C Coupon Holder Insulating front plate made of SiO 2 Redesigned front side to allow insulation to be flush with coupon Old Holder New Holder plus SiO 2 faceplate Gas Flow Test coupon Inconel Holder Tube exit SiO2 Face Plate Test Coupon

Deposits in Tube Deposits build up in the tube over successive runs Less ash impacts the coupon Affects capture efficiency Some tests were performed after large amounts of buildup occurred Data points considered outliers Solution: Routine cleaning of tube Deposits 8

Correcting for Ash Deposition in Tube Measured mass of deposit in SiC tube – When accounting for the mass deposited in the tube, the capture efficiencies of the new facility match those of the old facility 9

Recent Results Time-Dependent Test Series A test series investigating the time-dependent nature of deposit growth was performed Tests conducted for 20, 30, 40, and 60 minutes T g = 1250°C Capture efficiency, surface roughness (Ra), and deposit thickness are measured and calculated with respect to time 10

Recent Results °C Subbituminous Coal Flyash 11 Equilibration TubeCoupon

Recent Results 12 Wyoming Powder River Basin Coal Flyash 1250  C

Recent Results 13 Began temperature-dependent series Investigate the influence of gas temperature (T g ) on deposition Vary T g (1250°C °C) while using backside cooling to keep the initial surface temperature constant Only completed a few tests and low end of T g range Using flyash samples from bituminous and subbituminous coals

Recent Results 14 SubbituminousBituminous

Conclusions 15 Results from the new SiC facility compare well with results from the old inconel facility Surface roughness and deposit thickness both increase linearly with time at a given gas temperature while capture efficiency increases non- linearly Ash composition affects the manner in which ash deposits on the surface bituminous (higher melting point) deposits less evenly and depends more on a localized activation point